Specifically, but not exclusively, the invention can be advantageously used in a system for conveying pressurised fluid in the context of various hydraulic and/or industrial applications.
As shown in FIG. 1, the prior art comprises rotatable joints 100 formed by a first element 101, connected to an external system, and by a second element 102 to which a hose is fixed. These rotatable joints are those interposed, in use, between the hose and the external system to permit the relative rotation of the hose in relation to the external system.
The first element 101 comprises an end 101a connected to the external system and another end 101b, opposite the end 101a, comprising a threaded cylindrical portion 103 (male). The second element 102 comprises in turn a respective end 102a in which a threaded cylindrical internal cavity 104 (female) is defined which is arranged for being connected to the threaded cylindrical portion 103 of the first element 101, and an end 102b connected to the hose—opposite the end 102a. In use, screwing the second element 102 to the first element 101 is provided (as indicated schematically by the arrow F).
The first element 101 and the second element 102 further comprise respective internal holes that extend along the entire longitudinal extent thereof (defining in practice a single channel that extends axially over the entire joint) in such a manner that a pressurised fluid can traverse the rotatable joint from the external system to the hose, or vice versa.
The first element 101 is made in such a manner as to permit relative rotation between the threaded cylindrical portion 103 (and thus the second element 102 connected thereto) and the end 101a connected to the external system, such that the hose can rotate with respect to the external system to which it is connected by the joint.
A drawback of prior-art rotatable joints is that the pressurised fluid can exit the joint at the threaded connection between the first element 101 and the second element 102. This is very harmful, as these leaks of pressurised fluid to the outside pollute the surrounding environment and dirty the joint externally. Further, such leaks constitute a waste that causes an increase in costs.
Another drawback of known joints is the fact that the rotation movements of the hose in relation to the external system can cause accidental unscrewing of the second element 102 from the first element 101. This must be absolutely avoided because the sudden opening of the joint would cause a complete leakage of pressurised fluid with a consequent arrest of the flow of fluid into the system until the joint is restored.
A further drawback of known joints is the significant longitudinal dimension thereof, substantially determined by the sum of the longitudinal extents of the first element 101 and of the second element 102 (from which the longitudinal extent of the threaded cylindrical portion 103 is subtracted).